I think yours is a defensible position, but I'm not sure I agree with it. Scammers, while not posing immediate physical danger to others, can still pose enormous harm to many people. Banning them from engaging in various financial positions may not prevent them from running scams from outside the normal financial system.

For this person, I think I could support just a fine and a ban on working in the finance industry. I think it's likely he regrets what he did, and is unlikely to cause further harm to society. But there are people like Bernie Madoff (and people who only aspire to be as big a scammer as Madoff) who I think pose a continued, further harm to society.